It is common practice in the hose art to use barbed hose fittings to affix a hose fitting to a hose assembly. These end fittings are commonly attached to the hose by methods such as crimping to retain the fitting and to prevent the fitting from being pulled off of the hose assembly.
In today's increasingly more complex industrial and commercial environments, hoses and hose assemblies must be able to withstand harsh and highly demanding extremes of conditions. For example, hose assemblies are subjected to environments of extreme temperature and/or highly corrosive fluids. Chemically unreactive non-metallic fittings are particularly desirable when the hose is to be used in a corrosive environment. Furthermore, non-metallic hose fittings are generally lighter in weight and, in some instances, cheaper than conventional metallic hose fittings.
Current plastic end fitting designs require a heavy crimping force be applied about a collar around the hose and assembly to completely seal the interface between the end fitting and the hose to provide a fluid tight seal and to provide sufficient resistance to pull-off of the end fitting. In the typical environment in which a fuel hose and its associated components operate, continuous thermal-cycling can take place which has a tendency to induce a high degree of heat deflection in current plastic end fittings. The principal drawback of current end fitting designs is that the stress created by the crimp of a collar around a hose and end fitting magnifies the heat deflection effects caused by thermal-cycling. Additionally, the large crimping forces required to affix the end fitting to the hose can cause perforations or cuts to be formed in the hose which allow for the permeation of volatile fluids flowing therethrough.
A typical example of an end fitting which is inserted into a hose and affixed by crimping a collar around the hose and end fitting is shown in U.S. Pat. No. 4,664,424 to Smith. Unfortunately, the forces used to compress the hose between the end fitting and the crimp collar can be so great that they cause perforation or cutting of the hose, leading to permeation, leakage, or failure of the hose assembly at the point where the damage to the hose takes place. Frequently, this type of damage takes place where the hose is tightly pressed against barbs, ribs, or grooves disposed on the portion of the end fitting inserted within the hose. That is, the hose is pressed against edges or protrusions on the ribs or barbs when the crimp collar is compressed about the hose assembly and this locally intense pressure point can cause the above-mentioned damage to the hose. Additionally, damage to the hose can occur when the hose is allowed to rotate about the insert portion of the end fitting thereby potentially causing damage to the hose from the rubbing or cutting action of the ribs or barbs against the interior surface of the hose.
Various approaches have been described for offering increased resistance to end fitting pull-off including increased crimping force and/or the use of some form of mechanism to prevent the rotation of the hose about the insert portion of the end fitting. Such a mechanism is disclosed in European Patent Application Number 0066742 wherein a series of longitudinally disposed teeth are used to prevent axial rotation of the hose about the end fitting. A drawback to this method, however, is that the ridges or barbs can still cause perforation or damage to the hose.
British Patent Application Number 2216971 discloses a hose end fitting in which a stem portion including a plurality of barbs in which the barbs each have a progressively increasing angle to reduce the incidence of failure of the hose at the stem. U.S. Pat. No. 5,211,429 to Charlson et al. discloses a pipe fitting having at least two axially spaced annular barbs wherein each barb is provided with a staggered angle or back rake configuration. The barbs are utilized to restrict movement of a sleeve away from a pipe sought to be joined. In particular, the barbs of the sleeve compress the pipe radially inwardly and prevent its movement. The Charlson et al. patent discloses that the staggered angle or back rake configuration assists in the compression of the exterior surface of a pipe sought to be joined thereby preventing relative longitudinal movement therebetween.
A common coupling in use today includes a metal housing which receives a metal male member having a circumferential flange. The housing typically includes an O-ring for sealing the male member therein. The male member is secured within the housing by a plurality of spring loaded detents which spring open to allow insert for the insertion of the male member and flange and then springs closed to prevent withdrawal of the male member. However, this type of coupling allows for "end play" of the male member within the coupling. This "end play" can cause deterioration or displacement of the O-ring leading to leakage and failure of the seal therebetween.
Therefore, it would be advantageous to have an end fitting for a hose assembly which reduces or prevents barb-induced perforation of the hose and the resultant permeation of fluids flowing therethrough. Additionally, it would be advantageous to have an end fitting which further reduces end fitting-induced damage to a hose by preventing axial rotation of the hose about the end fitting. Additionally, it would be advantageous to have an end fitting which requires less crimp force than previous end fitting designs thereby eliminating excess stressing or prestressing of the insert portion of the end fitting and preventing damage to the hose caused by excess compression of the hose material against the ridges or barbs of the insert portion of the end fitting. Furthermore, it would be advantageous to have an end fitting which eliminates the drawbacks of the prior art end fittings discussed above.